Means and techniques for sensing and controlling temperatures



June 26, 1962 R. D. GRAYSON 3,040,581

MEANS AND TECHNIQUES FOR SENSING AND CONTROLLING TEMPERATURES Filed Dec. 24, 1959 INVENTOR. RICHARD o. GRAYSON By as TTORNEYS United States Patent Of MEANS AND TECHNIQUES FOR SENSING AND CONTROLLING TEMPERATURES Richard D. Grayson, La Canada, Califl, assignor to General Controls Co., Glendale, 'Calif., a corporation of California Filed Dec. 24, 1959, Ser. No. 861,941

8 Claims. ((31. 73-3683) .The present invention relates to improved means and techniques for sensing temperature conditions and for actuating various control means in accordance with the conditions sensed by the sensing elements. In general, the present sensing element may be employed generally wherever it is desired to sense a temperature and to operate a control in accordance with the temperature sensed; and while the same is described herein with reference to a water heater control, it will'be apparent that other usesmay be made of the same and in general the same may be used where heretofore bimetallic elements have been used for sensing temperature.

Briefly, the present invention involves the use of a material such as various rubber compounds having a high active thermal expansion and suitably housed with respect to a member movable in accordance with expansion of such material.

An object of the present invention is to provide an improved temperature-sensing means of the character indi cated above.

A specific object of the present invention is to provide an improved temperature-sensing device which incorporates a suitable material which allows production of a high active thermal expansion device in a relatively small package at very low cost.

Another specific object of the present invention is to provide an improved temperature-sensing device immersed in a housing which is impervious to fluids in such housing so that such fluids may have no detrimental effect on the sensing device or elements of the sensing device have no detrimental effect on the fluids or lining of the container for such fluids.

Another object of the present invention is to provide an improved thermal sensing device of this character which avoids necessity of heat insulation so that the device may respond to thermal conditions Without substantial time delay.

The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. This invention itself, both as to its organization and manner of operation, together with further objects and advantages thereof, may be best understood by reference to the following description taken in connection with the accompanying drawings in which:

FIGURE 1 illustrates a device embodying features of the present invention.

FIGURE 2 illustrates a modified form of the arrange- .ment shown in FIGURE 1 for obtaining a multiplication effect;

As disclosed in the drawings, there is exemplified a hot water tank having a metal wall 10 with a suitable lining such as a lining of glass L1 for confinement of liquid whose temperature is sensed and controlled by the device now described.

Protruding through an apertured circular apertured por- 1 tion 10A of the wall 10 and suitably welded thereto is a 1 closed-ended well or cylindrical member 12 which extends into the confines of the hot water tank and which also may be suitably coated with a glass coating 11.

This cylindrical member 12 is closed at its inner end and adjacent thereto is an internally tapered threaded portion 12A for screw-threadedly receiving the tubular case 14.

3,040,581 Patented June 26, 1962 2 The screw-threaded connection comprises a A" standard tapered pipe thread. i

The case 14 has its internal end closed and is suitably formed as, for example, to provide a conical wall portion 14A that provides a seat for a complementary shaped insert 15 of a special material having properties described later.

The insert 15 is contacted by a spring-biased piston 16 which is slidably mounted in the cylindrical portion 143 of the case .14, and having, for example, a very small clearance between such metal piston 16 and the metal case 14, such clearance being preferably in the range of .0003" to .0006" so that the same may move freely in such cylindrical portion while preventing extrusion of the in-- sert 15.

This movable piston 16 has a rod 17 attached thereto for movement therewith for purposes of actuating a cont-rolled device such as, for example, an electrical switch to an On and Off position in accordance with the temperature sensed by the insert 15.

Normally the insert 15 is under considerable compression .by the prestressed coil compression spring 19 having one of its'ends seated on movable piston 16 and the other one of its ends suitably seated on a stationary supporting element which may, for example, be attached to the tank wall 10 itself.

The insert 15 is of a material which may, for example, be a rubber compound having a high active thermal eX- pansion rate which moves the piston 16 to the left in FIGURE 1 upon increase in temperature of the insert 15. The plastic nature of the rubber compound allows it to conform to the surfaces of the piston 16 and adjacent walls of the case 1'4 when adequately pressured by the' coil compression spn'ng 19. The insert 15 may be of suitable material such as, for example, an elastomer such as those containing silicon or of a material known as Viton, a rubber compound produced by The DuPont Company, or a fluorinated silicon type material known as LS-53 in the trade. Materials of this character may have an expansion rate which is very large compared to the expansion rate of copper, i.e. the same may, for example, have an expansion rate 40 times that of copper.

It will be seen from this typical construction that the elements of the sensing device are not in communication with the liquid and this has the advantage in that introduction of foreign materials into the tank which can be elec trolytically antagonistic to the walls of the tank is obviated.

Further, this construction permits a continuous glass-- lined surface inside the tank.

It is also observed that the case 14 is screw-threaded into the well 12 and this provides a means whereby the compression forces normally exerted on the insert 15 by the spring 19 may be adjusted, simply by turning the case 14.

It will be observed further that by providing a tapered pipe thread for this purpose, there is good heat conduction between the Well 12 and the case 14.

In the modification shown in FIGURE 2, magnification of motion is produced. The insert 114 is generally of the same construction as in FIGURE 1, but in this case the expansible element 115 of the same composition as in FIGURE 1 is confined with the cylindrical portion 118 within which projects the movable rod 117 of diameter substantially less than the cross-sectional area of element 115. The rod 117 having a suitable flange 117A thereon, for example, in the form of a snap ring, is biased to the right in FIGURE 2 by the coil compression spring 119 and the expansive forces developed in the temperature sensing element 115 moves the control rod to the left against the bias of spring 119 so that relatively small rod 117 than is the ease in FIGURE 1.

While the particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

I claim:

1. Temperature responsive means comprising a tubular well having a closed end, a tubular casing screw-threaded in said well adjacent the closed end thereof, a temperaturesensing element comprising a temperature-expansible member having one end thereof abutting the threaded end of said casing, a piston slidably mounted in said casing and abutting the other end of said member, means biasing said piston in engagement with said member, and a rod attached to said piston and extending axially of said piston, said casing extending outwardly of said well whereby the same may be turned in said well to adjust the force applied by said biasing means to said sensing element.

2. An arrangement as set forth in claim 1 in which said well forms an inwardly protruding portion of a liquid heater on which the same is mounted.

3. An arrangement as set forth in claim 1 in which said member comprises an elastomer containing silicon.

4. An arrangement as set forth in claim 1 in which the screw-threaded connection between the Well and casing is a tapered pipe thread for good heat conductivity between the well and casing.

5. Temperature-responsive means comprising a tubular well having a closed end, a tubular casing screw-threaded in said well adjacent the closed end thereof, a temperaturesensing element in heat-conducting engagement with the threaded end of said casing, piston means slidably mounted in said casing and abutting said member, and means biasing said piston means against the expansible forces developed in said element, said casing extending outwardly of said well whereby the same may be turned in said well to adjust the force applied by said biasing means to said sensing element.

6. An arrangement as set forth in claim 5 in which said piston means abuts the entire cross-sectional area of said element.

7. An arrangement as set forth in claim 5 in which said piston means abuts a portion of the cross-sectional area of said element.

8. An arrangement as set forth in claim 1 in which said piston is of rigid non-deformable material.

References Cited in the file of this patent UNITED STATES PATENTS 899,313 Maurer Sept. 22, 1908 1,776,240 Wunsch July 9, 1929 1,890,909 Lincoln Dec. 13, 1932 2,534,497 Albright June 12, 1947 2,598,351 Carter Apr. 30, 1948 2,924,083 Spase Feb. 9, 1960 

